It's a Ghost! No, It's a Stellar Nursery

Astronomers using the Chandra X-ray Observatory (CXO) and the James Webb Space Telescope (JWST) studied a wispy region of the Carina Nebula. There, they found a ghostly-looking cloud that seemed to float alone among other clouds of gas and dust. The discovery came just in time for Halloween. Yet that little cloud is not the soul of a dead star. Instead, it is a part of the nebula that has been busy making batches of hot, young stars.

By looking at this region in X-rays and infrared light, astronomers can see the cloud's structure and the stars it has formed. This also helps them learn more about the larger Carina Nebula, which lies more than 7,500 light-years from Earth.

Many people know one brilliant and strange object in the nebula: Eta Carinae. It looks like a single star, but it is actually a binary system. Its combined brightness is about 5 million times that of our Sun. From time to time, this object brightens and dims. This is probably caused by clouds of condensed dust that gather around the binary stars. In the 1840s, it had a huge outburst called the "Great Eruption." That event threw tremendous amounts of gas and dust into space. Since then, it has had other, smaller outbursts.

The Carina complex is a huge diffuse nebula. It holds a collection of newborn stars inside a sea of star-making gas and dust. The region continues to produce new stars, many of them extremely bright and massive. Many telescopes have studied it, especially the Hubble Space Telescope and JWST. Each view gives new clues about what the cloud is made of and what objects it contains. Astronomers also keep watch on Eta Carinae because its primary star is a luminous blue variable. That star is likely to explode as a supernova. When it does, shock waves will reshape much of the nebula. They will probably set off new rounds of star birth.

Eta Carinae is a fascinating subject, but the nebula also contains places such as the Keyhole Nebula. The Keyhole is a dark, cold molecular cloud that covers about 7 light-years of space. Ionizing radiation from the nearby Eta Carinae binary is shaping the Keyhole and eating it away.

There is also the open cluster Trumpler 14. It is a grouping of more than 2,000 OB-type stars spread across about six light-years. These stars are massive and short-lived, and they shine very brightly in ultraviolet light. They are also very young. Their ages range from about 300,000 to 500,000 years.

The ghostly nebula that CXO and JWST imaged is still making stars at its heart. At the same time, ionizing radiation from the nearby Eta Carinae binary and from hot young stars is eating away the cloud's material. Thanks to that "cannibalizing" ultraviolet radiation, the cloud has formed several comet-like knots. Astronomers often call them cometary globules because of their familiar shapes. The Carina Nebula is not the only place where such knots appear. Astronomers have seen them in other star-forming regions and in planetary nebulae. In planetary nebulae, stellar winds collide with material that a dying star like the Sun has already ejected. Those collisions shape similar knots in clouds of gas and dust.

Since these stars will have much shorter lifetimes than the Sun, this region will someday look more like a stellar graveyard. The remains of the stars we see as newborn today will, in tens of millions of years, become ghosts of their former selves. They will spread their materials into interstellar space.